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Author Topic: Long Range Discussion: Winter 2020-2021  (Read 42940 times)

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Offline BRUCE

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Re: Long Range Discussion: Winter 2020-2021
« Reply #315 on: November 14, 2020, 08:39:43 PM »
Hey now, show some snow love for your friends in east TN.  ;)
it must going be a major apps runner Jaycee... lol
Come on severe wx season...

Offline JayCee

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Re: Long Range Discussion: Winter 2020-2021
« Reply #316 on: November 15, 2020, 03:05:22 PM »
At this point, I think this winter will be unpredictable--like most things these days.  Yes, we have a moderate to strong La Nina.  But we also have very warm water in the northeast Pacific. Normally, the two don't coincide. It seems we'll have periods of unusual warmth, but periods of cold mixed in.  When the pattern changes, watch out! A strong winter storm will ride the dividing line.  Right now, I would put west and middle TN in the best chance of seeing snow and ice when the pattern flips.  East TN may see their best chance of winter weather right after the flip if we can get at decent storm to come out of the Gulf.  Changeable would be the best description. Some days in the 70's, followed by a few barely above freezing.
It's obvious the climate is in a state of flux. Seasons don't follow the normal patterns.  We have autumns that are hot, followed by springs that are cold. 2020 is the first year in a long time that seemed "normal," despite the previous years of weather extremes.  But, I think this winter is treading new ground.  There are few, if any, analogs where we had a strong La Nina with warm water in the North Pacific.  Unusual patterns create unusual weather.  We'll just have to learn as we go.  I think there is a country song that says the same thing, but this year has been far from a dance.   ::blowtorch:: ::snowman::
"For many years I was self-appointed inspector of snowstorms and rainstorms, and did my duty faithfully, though I never received one cent for it.." 
Henry David Thoreau

Offline StormNine

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Re: Long Range Discussion: Winter 2020-2021
« Reply #317 on: November 15, 2020, 06:09:30 PM »
I do think we have a short-lived period of true winter during this winter season. If we can squeak in a Strat Warming event with the active normal stream a period like that would likely open up sometime between New Years and Valentine's Day. 

La-Nina climo and analogs definitely support such a timeframe.  It would probably last 3-4 weeks at best, but that would be better than the last two winters.  The late January 2009 timeframe or the late December 98 to about the first 10 days or so of 1999 are about what we would be looking at.  Our risk of a winter storm and especially a ice storm would be probably above average at that time.   


Offline BRUCE

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Re: Long Range Discussion: Winter 2020-2021
« Reply #318 on: November 16, 2020, 02:04:29 PM »
Our current northern pacific pattern this month is matching up with the November of 98 pretty
Nicely ...  be interesting see were we go from here .
Come on severe wx season...

Offline schneitzeit

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Re: Long Range Discussion: Winter 2020-2021
« Reply #319 on: November 16, 2020, 02:45:04 PM »
Thanks to all who have been contributing to this thread. I appreciate it. Many of you are inadvertently helping me learn about our climate and how to use analogs in weather forecasting.
Nashville's Big Hits (since '98)

April 16, 1998 Tornado
January 16, 2003 Snowstorm
Summer 2007 Drought
May 1-2, 2010 Great Flood of Nashville
June 2012 Record Heat Wave
February 2015 Tennessee Ice Storm
January 22, 2016 Winter Storm Jonas
March 3, 2020 Tornado

Offline Eric

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Re: Long Range Discussion: Winter 2020-2021
« Reply #320 on: November 16, 2020, 03:07:16 PM »
Thanks to all who have been contributing to this thread. I appreciate it. Many of you are inadvertently helping me learn about our climate and how to use analogs in weather forecasting.

Singular best tip about using analogs in winter?

Don't use them.  Trying to nail down winter in Tennessee is like trying to hit a knuckle-slurve when you're expecting a fastball.  Teleconnections can give you a general idea - la nina, el nino, MJO, etc - but trying to use them for anything more than generalities is a wasted effort.  Three different sections dominate the state and all three carry vastly different climatological identities during the winter months.
#tSpotter Coordinator for Rutherford and Warren Cos. (@WarrenSevereWx and @RuthSevereWx)

Offline Curt

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Re: Long Range Discussion: Winter 2020-2021
« Reply #321 on: November 16, 2020, 03:09:52 PM »
Our current northern pacific pattern this month is matching up with the November of 98 pretty
Nicely ...  be interesting see were we go from here .

No its not. I posted some maps last week that show some significant differences. The 98-99 La Nina at THIS time was warner east and colder west with a MUCH colder NE Pacific. The current La Nina is basin wide but coldest in the central region (3.4) than the others. In fact, the latest index for 3.4 warmed to -1.0 which is a significant change from the -1.7 a few weeks ago. The entire basin warmed in fact over the last week although keeping in mind that can change, too. A significant difference from almost all moderate- strong La Nina's is the ridiculous warm pool in the NE Pac. 2017-18 had one but nothing as warm as it is currently. If there's more warming over the next couple of weeks, this La Nina might start declining. We will have to see where it goes. The warming this week was significant though.

Offline BRUCE

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Re: Long Range Discussion: Winter 2020-2021
« Reply #322 on: November 16, 2020, 03:18:00 PM »
No its not. I posted some maps last week that show some significant differences. The 98-99 La Nina at THIS time was warner east and colder west with a MUCH colder NE Pacific. The current La Nina is basin wide but coldest in the central region (3.4) than the others. In fact, the latest index for 3.4 warmed to -1.0 which is a significant change from the -1.7 a few weeks ago. The entire basin warmed in fact over the last week although keeping in mind that can change, too. A significant difference from almost all moderate- strong La Nina's is the ridiculous warm pool in the NE Pac. 2017-18 had one but nothing as warm as it is currently. If there's more warming over the next couple of weeks, this La Nina might start declining. We will have to see where it goes. The warming this week was significant though.
must be looking at wrong maps  Curt  seriously
Come on severe wx season...

Offline Curt

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Re: Long Range Discussion: Winter 2020-2021
« Reply #323 on: November 16, 2020, 03:25:49 PM »
must be looking at wrong maps  Curt  seriously
Seriously- these are all from NOAA:

November 1998



Current 2020


Changes over the last week

Offline Crockett

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Re: Long Range Discussion: Winter 2020-2021
« Reply #324 on: November 16, 2020, 03:47:17 PM »
must be looking at wrong maps  Curt  seriously

Or maybe he just isn't blinded by an effort to wish-cast record warmth and severe weather outbreaks.

Offline BRUCE

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Re: Long Range Discussion: Winter 2020-2021
« Reply #325 on: November 16, 2020, 07:48:32 PM »
See I posted a merit post... I get bashed. Lol people will see what this winter will be analog to. Not going worry or argue bout it.  Get used to warmer winters anyways due to big climate change taking over . Yeah I went there... 98 99 top analog this winter up coming
Come on severe wx season...

Offline Curt

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Long Range Discussion: Winter 2020-2021
« Reply #326 on: November 16, 2020, 10:18:45 PM »
See I posted a merit post... I get bashed. Lol people will see what this winter will be analog to. Not going worry or argue bout it.  Get used to warmer winters anyways due to big climate change taking over . Yeah I went there... 98 99 top analog this winter up coming
No, I posted facts that were contrary to your anecdote. A thorough and productive discussion of your opinion would have been preferred.

Offline StormNine

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Re: Long Range Discussion: Winter 2020-2021
« Reply #327 on: November 17, 2020, 04:18:27 AM »
The strong Polar Vortex may be more of a problem for us than the Pacific.  contrary to the media, when you have a strong Polar Vortex especially one centered in Northern Siberia that acts to lock the cold air in the place and floods the mid-latitudes with Pacific air instead yuck!  These unusually strong PV's of the past 2 years may be a result of melting arctic ice in the past few years but I'm not fully sure.

If we can have a strat warming event or something comes through and causes it to buckle say next month or Early January then we would have a reservoir of cold arctic air to play with potentially.   When factored in with the La-Nina could create quite the battlezone for our area when and if that does occur.   


If it doesn't than we may resemble last winter more than we would like.   

Offline StormNine

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Re: Long Range Discussion: Winter 2020-2021
« Reply #328 on: November 17, 2020, 05:17:16 AM »
I imagine that at least the first 3 weeks of December will probably be mild and dry with no major weather events.  Pretty much copy and paste from November but what happens with the polar vortex is important.  I do think at least some of it comes down and we have a 3-4 week of pretty solid winter that will resemble the late Dec/Early to Mid-January period of 1998-99 and 2017-18 sometime between Christmas and Valentine's Day before the Bruce portion of the winter takes over sometime in the 2nd half.   

Offline JayCee

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Re: Long Range Discussion: Winter 2020-2021
« Reply #329 on: November 17, 2020, 06:18:23 AM »
The end of the 6Z run of the GFS seems to have upper heights building in eastern Canada that begin to poke up toward Greenland.  Correspondingly, long range outlooks forecast the NAO (along with AO) to dive toward negative territory.  Any amount of blocking in the polar regions may change up the weather as we head into December.  The question on my mind is: how low will it go, and how long will it last? 
"For many years I was self-appointed inspector of snowstorms and rainstorms, and did my duty faithfully, though I never received one cent for it.." 
Henry David Thoreau

 

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